opengl: Fix multiple render target setup with glDrawBuffers
opengl: Fix multiple render target setup with glDrawBuffers

googlearchive/nxt-standalone,googlearchive/nxt-standalone,Kangz/nxt-standalone,Kangz/nxt-standalone,Kangz/nxt-standalone,googlearchive/nxt-standalone,Kangz/nxt-standalone,googlearchive/nxt-standalone